An engine bench is known as a device to be used for testing engine performance (refer to Patent Literature 1). An engine bench is a testing device configured to evaluate whether a test engine includes predetermined performance or not, and the test engine is attached to a bench test machine (an engine bench). An output shaft of the engine is connected with a dynamometer via a torque meter, and rotation force of the engine is absorbed by the dynamometer. A dynamometer is generally controlled by feedback control, so that the rotational frequency of the dynamometer is controlled to be a target rotational frequency.